Hello,

blob.major_axis_line() is a tuple for a line but not a line. Then the only way I found to calculate the length is:

```
maja = blob.major_axis_line()
lmaja = int(round(math.sqrt((maja[2]-maja[0])**2 + (maja[3]-maja[1])**2)))
```

Then I wonder if it is possible to simply get the properties of blob.major_axis_line() like we can do with the methods of the line class which may be optimized.